Expansion of the Mexican rice borer (Lepidoptera: Crambidae) into rice and sugarcane in Louisiana

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive pest of sugarcane, Saccharum spp., rice, Oryza sativa L., and other graminaceous crops in the Gulf Coast region of the U.S. This study documents establishment and distribution of E. loftini in southwest Louisiana from 2009–2013. Traps baited with E. loftini female sex pheromones were used to monitor adult males near sugarcane, rice, and non-crop hosts in ten Louisiana parishes. Additional field surveys documented larval infestations in commercial sugarcane and rice. After the initial detection in 2008, no E. loftini were detected in Louisiana in 2009 and only two adults were captured in 2010. Trapping in 2011 detected E. loftini at 42 new sites and provided the first record of its occurrence in Cameron, Beauregard, and Jefferson Davis Parishes. Range expansion was limited in 2012, with only a single specimen recorded. Monitoring efforts in 2013 confirmed the presence of E. loftini in 30 previously unknown sites and three new parishes (Allen, Acadia, and Vermilion). During the course of this study, E. loftini expanded its range eastward into Louisiana 120 km from the Texas border (≈22 km/yr). Surveys of larval infestations provided the first record of E. loftini attacking rice and sugarcane in Louisiana. Infestations of E. loftini in rice planted without insecticidal seed treatments in Calcasieu Parish reached damaging levels. Pheromone trap captures were correlated with larval injury in adjacent untreated rice fields. Continued monitoring will be critical to better understand E. loftini ecology and improve pest management.